The objective of this SBIR project is to develop a new, solid state immunosensor with capabilities for use in homes, farms, factories and offices for on-site quantitative determination of hormones, drugs and toxins in biological fluids such as plasma, saliva, and urine. The principle of detection will be based on an enzyme- amplified, immunoelectrochemical solid state detector that can be coupled to different reporter-amplifier systems and modified to accommodate an array of sensors for different compounds. During Phase I, we intend to demonstrate the feasibility of developing the sensor and to determine if it will be able to give expected sensitive and quantitative measurements. Phase II research will focus on optimizing the sensor, introducing the capability for measuring multiple different substances simultaneously at multiple sites on a single probe, incorporating the probe into an easily-used device that obviates the need for pipetting and sample manipulation, and coupling the probe to instrumentation able to be used in the field. Results of this project will provide the basis for developing a system that is extremely easy to use, requiring little manipulation and no pipetting. The envisioned system will eliminate the need for subjective estimation of quantities, will avoid errors, and will be able to be used to estimate concentrations of multiple different hormones, drugs or other agents simultaneously in biological fluids by untrained personnel.